Antifreeze question

[Bobi and Dick McKee]

Today when I was checking my oil level I noticed the antifreeze was approaching the low level on the overflow tank.  The engine was cold and my question is should the level in the tank be checked when the engine and antifreeze is hot or cold?  Thanks in advance, Dick

[jc2]

Cold.  It's not uncommon for over flow tanks to have marks on the tanks indicating the recommended level of anti-fréeze when the engine system is cold or hot so your system must have them judging from the wording of your post.

[Barbaraok]

We only check when engine is hot.  If we see fluid in sight glass all good.  If not add in the morning just until it barely shows in site glass.    If you add without checking hot level, you will just have excess being thrown out.  

[Kirk W]

11 hours ago, jc2 said:

It's not uncommon for over flow tanks to have marks on the tanks indicating the recommended level of anti-fréeze when the engine system is cold .................

1

I believe that all of the overflow tanks now have that marking. I normally check everything just before I begin to travel and occasionally will when hot as well. The way I look at it when the engine cools down the coolant contracts and draws from the overflow tank so if it is too low at that time the radiator will draw air into it and not be completely full. On the other hand, if it should be a bit too full and the engine is hot, any excess will just spill out and be lost but no harm is done to the engine. 

[Barbaraok]

If you check when hot, and see fluid in the sight glass (or some other reference point) then the contraction of fluid as it cools will still leave plenty of fluid in the tank.  If you don't see fluid when hot, then you need to add because the needed 'surplus' isn't there.  

[Kirk W]

5 hours ago, Barbaraok said:

If you check when hot, and see fluid in the sight glass (or some other reference point) then the contraction of fluid as it cools will still leave plenty of fluid in the tank. 

Not all engines have a sight glass. Neither my gas nor my diesel has one, but the both have overflow tanks that have hot and cold levels marked. Our gasoline class A didn't have the sight glass either. 

[Bobi and Dick McKee]

Ours is a Cummins ISL9 in our Sportschassis.  I answered my own question today when I added antifreeze.  The cap had a warning do remove when hot, so I assume I should add when the engine is cool.  The over flow tank is about a gallon, yup real big, and there is still about a quart of expansion room with the antifreeze at the full mark.  The biggest problem here in Dillon Montana was finding antifreeze that met Cummins specs with something called fully formulated with SCA.. It's purple and I found it a a little Napa store.  Thanks for all the input.  Dick

[RBH]

 

On 6/23/2017 at 8:12 PM, Bobi and Dick McKee said:

Ours is a Cummins ISL9 in our Sportschassis.  I answered my own question today when I added antifreeze.  The cap had a warning do remove when hot, so I assume I should add when the engine is cool.  The over flow tank is about a gallon, yup real big, and there is still about a quart of expansion room with the antifreeze at the full mark.  The biggest problem here in Dillon Montana was finding antifreeze that met Cummins specs with something called fully formulated with SCA.. It's purple and I found it a a little Napa store.  Thanks for all the input.  Dick

Used to be all anti-freeze was green. Now there are so many different formulations that it can get confusing. My Freightliner with a Cat came with "long Life" antifreeze that needed SCA boosting occasionally. When it came time to replace the coolant I asked my dealer to use "Extended life" anti-freeze that does not require SCA boosting. Well they did not know or realize the difference and replaced it with the original "long life" stuff. Fortunately I found that "Fleet Charge" has a converter fluid that can change "long life" to "Extended life" so I was able to get the advantage of not having to keep up with SCAs without another full replacement . There are also test strips that can check the level of nitrates in the coolant (the SCAs that protect from cavitation corrosion).

[Bobi and Dick McKee]

My concern about finding the correct antifreeze was for warranty reasons.  Every tag on the cooling system and in the Cummins manual warned about only using anti freeze with SCA.  Dick

[NoDirectionHome]

It's actually a bit more complicated than that.  You really need to check with the test strips before adding.  Then either by adding a supplement or in my case a new filter that slowly releases the necessary additives you can maintain the proper chemical levels.  It's somewhat complicated and quite important in a diesel to get this correct.

[Bobi and Dick McKee]

We have our Sportchassis serviced about every 10k miles or once a year, which is half the mileage Cummings requires. 8 to 10k is about what we put on in a summer. Cummins A and B service both have antifreeze testing as part of that service. Dick

[Ray,IN]

On 6/23/2017 at 1:54 PM, Barbaraok said:

If you check when hot, and see fluid in the sight glass (or some other reference point) then the contraction of fluid as it cools will still leave plenty of fluid in the tank.  If you don't see fluid when hot, then you need to add because the needed 'surplus' isn't there.  

However, there can be a time when the cooling coolant withdraws all the "Surplus" coolant, then it sucks in air. That air can create an air bubble in the system, which in turn causes a hot spot, which in turn can result in engine damage.

I know that's a lot of "what if's" but, it's just easier to check coolant when cold as the operators manual recommends.

[Barbaraok]

I do check mine as specified in our owners manual - when it is hot.   The sight glass is located so that if coolant is showing when hot, then there is sufficient coolant present to allow for cooling down and contraction.   Obviously, if your set up is such that you have a tank that you can see the fluid, that you low and high levels, and different owners manual, then you do what that says.  I made the mistake of thinking that everyone with a diesel engine had a similar setup to ours.   Each RV manufacturer sets up the cooling system differently.   Since the guys at Cummins Coach Care facilities, as well as other diesel facilities have never batted an eye - indeed put in a new sight glass (they keep a supply on hand)  this winter since the other was coated over, our setup must be one that a lot of manufacturers use.